Baseball and softball batters often experience fatigue in their forearms after swinging a bat several times over a short interval. A force analysis indicates that this fatigue at least partially results from the bottom hand and the top hand opposing each other during the swing. In general, the bottom hand generally performs a pulling motion while the top hand generally performs a pushing motion. During the initial stages of the swing, as the bottom hand pulls and the top hand pushes, the barrel of the bat begins to descend into the plane of the pitched (or stationary) ball. During this time, the hands ideally rotate into the proper “power position,” in which the palm of the lower hand generally faces downward while the palm of the upper hand generally faces upward. There may be some variance due to differing pitch locations but, regardless, in the power position the two palms should generally face opposite directions while being essentially coplanar. To accomplish this hand-positioning, most batters need to rotate one or both of their hands during the swing.
U.S. patent application Ser. No. 13/795,916, filed Mar. 12, 2013, and U.S. patent application Ser. No. 13/958,309, filed Aug. 2, 2013, which are incorporated herein by reference, describe various ball bats in which a portion of the bat's handle is rotatable relative to the rest of the bat to facilitate positioning the batter's hands in the power position. These bat designs, however, cannot be used in Major League Baseball, or in other leagues that require the use of a one-piece, wooden bat.